<!DOCTYPE html>
<style>
.multicol {
    margin: 3em 0;
    width: 60px;
    -webkit-column-width: 20px;
    -webkit-column-gap: 0;
    column-fill: auto;
    height: 60px;
}
.square {
    width: 20px;
    height: 20px;
    background: green;
}
#test1 .layer { will-change: transform; }
#test2 .layer { will-change: opacity; }
#test3 .layer { will-change: top; position: relative; }
</style>

<p>If no compositing were present, there should be two green squares below. Since some elements are composited, and therefore not fragmented, the output is different.</p>
<div id="test1" class="multicol">
    <div class="layer"> <!-- first column -->
        <div class="square"></div>
    </div>
    <div class="square"></div>
    <div class="layer"> <!-- from first to second column -->
        <div class="square"></div>
        <div class="square"></div>
    </div>
    <div class="square"></div>
    <div class="layer"> <!-- from second to third column -->
        <div class="square"></div>
        <div class="square"></div>
        <div class="square"></div>
    </div>
    <div class="square"></div>
</div>

<div id="test2" class="multicol">
    <div class="layer"> <!-- first column -->
        <div class="square"></div>
    </div>
    <div class="square"></div>
    <div class="layer"> <!-- from first to second column -->
        <div class="square"></div>
        <div class="square"></div>
    </div>
    <div class="square"></div>
    <div class="layer"> <!-- from second to third column -->
        <div class="square"></div>
        <div class="square"></div>
        <div class="square"></div>
    </div>
    <div class="square"></div>
</div>

<div id="test3" class="multicol">
    <div class="layer"> <!-- first column -->
        <div class="square"></div>
    </div>
    <div class="square"></div>
    <div class="layer"> <!-- from first to second column -->
        <div class="square"></div>
        <div class="square"></div>
    </div>
    <div class="square"></div>
    <div class="layer"> <!-- from second to third column -->
        <div class="square"></div>
        <div class="square"></div>
        <div class="square"></div>
    </div>
    <div class="square"></div>
</div>
